As disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2009-123896, a printed circuit board inside the case of an electronic apparatus is normally secured to a supporting structure provided inside the case by means of fixing members, such as screws. The screws also serve as members for electrically connecting the printed circuit board to a ground provided inside the case of the electronic apparatus. In a general electronic apparatus, screws are commonly used for securing a printed circuit board. Since screws are used in many electronic apparatuses, there is a growing demand for an improved structure using screws.
In the above structure using screws, a solder connection is normally provided for electrical connection. The solder connection may have needle-like whiskers, and they may be a main cause of dust generated inside the electronic apparatus. Copper foil is normally used at positions where electric connection is required on the printed circuit board, but the copper foil may oxidize and become a copper oxide. Thus, the copper oxide may also be a main cause of dust.
To suppress the generation of dust and improve the reliability of an electronic apparatus, the solder connection and the copper foil are plated with gold in many cases. However, gold is costly, and the plating process necessitates disposal of a waste liquid, causing adverse impact on environment. Under the circumstances, there has been a demand for a process that can be used in place of the gold plating process.